This application claims priority from European Patent Application No. 050 23 355 filed Oct. 26, 2005, incorporated herein by reference in its entirety.
The invention relates to an evaporation device.
Oil evaporators are for example required for producing capacitors. Herein dielectrics, for example synthetic sheets, are provided with a metal layer. To avoid negative consequences for the capacitor following electric sparkovers, metal-free strips are provided on the synthetic sheet. These metal-free strips are generated thereby that at specific sites an oil film is applied onto the synthetic sheet. The metal vapor, preferably aluminum, subsequently applied onto the synthetic sheet, cannot become attached in place at those sites at which the oil film is located.
An evaporator device with a nozzle is disclosed in JP 10008241. In this document the material to be evaporated is evaporated in a crucible, wherein it escapes via a nozzle and migrates in the direction toward the substrate where it lastly condenses. By means of a valve the quantity of the escaping vapor can be controlled. However, this device is solely employed for evaporating metals.
A device for producing metal-free strips in sheet webs coated under vacuum, in particular for capacitors, is furthermore known, which comprises a tubular receptacle for accepting a separating agent, for example of oil (DE 39 22 187 A1). In the tubular receptacle closed by circular disk-shaped end parts, is located a heating rod, all around of which flows oil. In the receptacle is furthermore located a vapor outlet tube, one end of which projects above the oil level and at whose other end is provided an outlet nozzle. The outlet nozzle is herein located beneath the oil reservoir.
A device for evaporating oil is furthermore known, with the oil being disposed in a tube-like vessel (JP 2001 279425). This vessel has several openings arranged in a row, from which the vapor can escape.
In another device the oil is located in an elongated tank (JP 2004-214185). This tank has several openings which are arranged in a row and which assume the form of a nozzle bar. By means of this nozzle bar it is possible to coat very large areas.
A vaporisation device is known comprising a container as well as a seal-off device and a jet body (DE 198 48 177 A1). With this device the container is connected to the seal-off device and the seal-off device is connected to the jet body via a supply line.
A method for localized application of a parting means with a vaporizer onto moving substrates is also known (EP 1 493 836). This vaporizer comprises two chambers arranged one above the other and connected via a channel. The material to be vaporized is disposed in the lower chamber and can pass in the upper chamber through the channel. By means of a voltage controlled proportional valve the quantity of vapor passing in the upper chamber per time unit can be controlled.
The present invention addresses the problem of providing an evaporator device for the evaporation of oil, which comprises a seal-off device on the nozzle.
The problem is resolved according to the present invention.
The invention consequently relates to an evaporator device with a receptacle for holding material to be evaporated. With this evaporator device an oil film can be applied onto specific sites of a sheet to be coated, wherein this sheet is coated in a further step with aluminum or zinc. At those sites at which the oil film is disposed, no aluminum or zinc is deposited. With the aid of a rod valve precise application of the oil onto the sheet is ensured. This rod valve is driven by a stepping motor, which can release oil vapor in percentage fractions.
With this evaporator device substrates, preferably metallized synthetic films, can be coated with a solid or liquid mixture of saturated or unsaturated hydrocarbons. However, the use of fully synthetic oils is also possible. Therein a synthetic sheet, as shown in JP 2004-214185, can be guided by means of rollers over the evaporator device described here.
With this evaporator device the metal layer or the layers on the synthetic sheet are uniformly coated, since it is possible to meter the oil vapor. Subsequent coating of the oil layer with further materials utilizing this evaporator device also does not present any problems.
Thereby that beneath the outlet nozzle a seal-off device is disposed, the quantity of escaping oil vapor can be regulated. It is ensured that oil vapor does not continuously escape from the unit, especially since the seal-off device can also be closed completely. Therewith the escape of oil vapor is no longer possible. This has in particular the advantage that the heating process does not need to be interrupted, if, for a short time, no substrate is moved over the evaporator device.
A further advantage lies therein that the pollution through escaping oil vapor is reduced to a minimum.
The loss of oil through continuous evaporation is therewith considerably decreased.
An embodiment example of the invention is depicted in the drawing and will be described in the following in further detail.